Re: Replace selective-display in Gnus

[Reiner Steib <reinersteib+gmane@imap.cc>]

On Sat, Aug 29 2009, Stefan Monnier wrote:

>> Could someone propose a patch how to use invisible overlays here?  It
>> should be compatible with Emacs 21 (and up) and XEmacs 21.4 (and up)
>> if possible.
>
> Here is the gnus-sum.el code I'm using nowadays.

Thanks.

> IIRC it's not 100% correct (the behavior is not quite the same as
> the current one).

What is the difference?  (I don't use this feature so I'll probably
won't notice it.)

> This includes unrelated changes, and uses remove-overlays which was
> new in Emacs-22.

As we need the old code for compatibility with older Emacsen, I think
I will install it with some (fboundp 'remove-overlays) conditionals.

Below are the relevant hunks (AFAICS) for review. Does anyone see a
problem with this?

--8<---------------cut here---------------start------------->8---
--- lisp/gnus/gnus-sum.el	2009-08-29 09:03:23 +0000
+++ lisp/gnus/gnus-sum.el	2009-08-29 14:14:56 +0000
@@ -3069,8 +3069,7 @@
   (setq buffer-read-only t		;Disable modification
 	show-trailing-whitespace nil)
   (setq truncate-lines t)
-  (setq selective-display t)
-  (setq selective-display-ellipses t)	;Display `...'
+  (add-to-invisibility-spec '(gnus-sum . t))
   (gnus-summary-set-display-table)
   (gnus-set-default-directory)
   (make-local-variable 'gnus-summary-line-format)
@@ -11281,26 +11287,25 @@
 (defun gnus-summary-show-all-threads ()
   "Show all threads."
   (interactive)
-  (save-excursion
-    (let ((buffer-read-only nil))
-      (subst-char-in-region (point-min) (point-max) ?\^M ?\n t)))
+  (remove-overlays (point-min) (point-max) 'invisible 'gnus-sum)
   (gnus-summary-position-point))
 
 (defun gnus-summary-show-thread ()
   "Show thread subtrees.
 Returns nil if no thread was there to be shown."
   (interactive)
-  (let ((buffer-read-only nil)
-	(orig (point))
+  (let* ((orig (point))
 	(end (point-at-eol))
 	;; Leave point at bol
-	(beg (progn (beginning-of-line) (point))))
-    (prog1
-	;; Any hidden lines here?
-	(search-forward "\r" end t)
-      (subst-char-in-region beg end ?\^M ?\n t)
+         (beg (progn (beginning-of-line) (if (bobp) (point) (1- (point)))))
+         (eoi (when (eq (get-char-property end 'invisible) 'gnus-sum)
+                (or (next-single-char-property-change end 'invisible)
+                    (point-max)))))
+    (when eoi
+      (remove-overlays beg eoi 'invisible 'gnus-sum)
       (goto-char orig)
-      (gnus-summary-position-point))))
+      (gnus-summary-position-point)
+      eoi)))
 
 (defun gnus-summary-maybe-hide-threads ()
   "If requested, hide the threads that should be hidden."

@@ -11349,22 +11354,26 @@
 will not be hidden.
 Returns nil if no threads were there to be hidden."
   (interactive)
-  (let ((buffer-read-only nil)
-	(start (point))
+  (let ((start (point))
+        (starteol (line-end-position))
 	(article (gnus-summary-article-number)))
     (goto-char start)
     ;; Go forward until either the buffer ends or the subthread ends.
     (when (and (not (eobp))
 	       (or (zerop (gnus-summary-next-thread 1 t))
 		   (goto-char (point-max))))
-      (prog1
 	  (if (and (> (point) start)
+               ;; FIXME: this should actually search for a non-invisible \n.
 		   (search-backward "\n" start t))
 	      (progn
-		(subst-char-in-region start (point) ?\n ?\^M)
+            (when (> (point) starteol)
+              (remove-overlays starteol (point) 'invisible 'gnus-sum)
+              (let ((ol (make-overlay starteol (point) nil t nil)))
+                (overlay-put ol 'invisible 'gnus-sum)
+                (overlay-put ol 'evaporate t)))
 		(gnus-summary-goto-subject article))
 	    (goto-char start)
-	    nil)))))
+        nil))))
 
 (defun gnus-summary-go-to-next-thread (&optional previous)
   "Go to the same level (or less) next thread.
--8<---------------cut here---------------end--------------->8---

Bye, Reiner.
-- 
       ,,,
      (o o)
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